"Sir Alex Ferguson said the 6-1 defeat to Manchester City was his worst day in football," says David Wallace. "Was it his biggest defeat as a manager?"

It was only the third time in 2,061 games, spread over 37 years, that a Ferguson team conceded six goals in a game. The others came in 1974, when East Stirlingshire lost 6-2 at Albion Rovers, and 1996, when Manchester United were trounced 6-3 by Southampton. Whether it was his worst defeat depends on whether you regard a 6-1 defeat as worse than a 5-0. (A 6-1 scoreline is better in terms of the league table but, well, 6-1.) The City game was not, however, the worst of Ferguson's entire football career: he was in the Falkirk side that lost 7-1 to Airdrie on 26 April 1971.

Here's a list of Ferguson's 17 managerial defeats by four goals or more, ordered by margin of defeat, goals conceded and then date.

NEGATIVE LEADERS

"Morton, in the Scottish First Division are leading the table after eight games but have a goal difference of -2," wrote Ross Smith. "Has a team ever led their league with a negative goal difference after so many games?"

Do you know of any other sides who have topped the table late in the season with a negative goal difference? Send your answers to knowledge@theguardian.com

MORE ECO-FRIENDLY FOOTBALLERS

Last week, we looked at players who give one about the environment, and here are a couple of other examples.

"I was once listening to Radio 1's Newsbeat around 10 years ago and there was a piece on the newly introduced LPG fuel," says Matthew Lutz, brother of celebrity stubble-carrier Tom Lutz. "They interviewed someone who was filling up their car with it – and it was none other than the then-Cheltenham Town defender and uber-Championship Manager legend Michael Duff."

Then there's the Guardian's finest. No, not Hadley Freeman. "I didn't bother answering this week as it seemed like the obvious answer (considering he is a Guardian [actually Observer] columnist), but I was surprised not to see the inclusion of David James. There was an article about the fact that he paid £2,500 to convert his car to run on (locally sourced) rapeseed oil, so I reckon he's a better shout than Moritz Volz's fold-up bike."

KNOWLEDGE ARCHIVE

"Down at the pub the other night, a friend of mine bullishly claimed he'd heard that a match was once postponed on almost 30 separate occasions. Is he having me on?" asks Jonathan Gainter.

Hail your friend, Jonathan, as he speaks the truth. Back in the icy winter of 1979, the Scottish Cup second-round clash between Inverness Thistle and Falkirk had to be postponed no fewer than 29 times. The original date for the game was 6 January, but the clubs had to wait 47 days until the Kings Mills ground was eventually declared playable, on 22 February. When the match finally took place, four first-half goals helped Falkirk seal their spot in the third round. However, because of the 71-day period between the second-round draw and Falkirk's win, Billy Little's side were forced to visit Dundee just three days later in round three, where a late penalty ended their cup journey.

Incredible as these 29 postponements are, the tie is still eclipsed by another Scottish Cup game that took place 16 years earlier, when sub-zero conditions again played havoc with the fixture list – and not just in Scotland but all across Britain. More than 400 English league and cup matches fell victim to the weather and the season had to be extended by a month on both sides of the border. While one FA Cup third-round tie between Coventry and Lincoln eventually took place at the 16th time of asking, the clash between Airdrie and Stranraer was busy setting a British record of 33 postponements. For Airdrie it was 34th time lucky as they ran out 3-0 victors.

Incidentally, the worst day of domestic cancellations didn't occur in 1962-63. That honour went to 3 February 1940, when only one of 56 wartime league matches beat the weather. Plymouth made the most of their moment in the limelight with a 10-3 thumping of Bristol City.

Can you help

"Watching Liverpool v Man U made me think, Ryan Giggs and Jamie Carragher must have played each other 30-odd times in club football – and regularly as direct opponents (left wing v right-back). Who can beat that?" says Chris Atkinson.

"What was the longest transfer, in miles, in the UK? I'm looking at a InverCaly to Truro City kind of thing," says Fraser Thomas.

"I was wondering when there were the most London clubs in the top flight of football (both when there were 20 or 22 teams in the league)? It might be 1991-92 with seven (QPR, Spurs, Arsenal, Chelsea, Wimbledon, Crystal Palace, West Ham)?" says Aaron.